import { useMemo, useState } from "react";
import { ActivityIndicator, Alert, View } from "react-native";
import { router, useLocalSearchParams } from "expo-router";
import * as LocalAuthentication from "expo-local-authentication";
import { useTranslation } from "react-i18next";
import { useSafeAreaInsets } from "react-native-safe-area-context";
import { Button } from "@/components/ui/Button";
import { Field, SwitchRow } from "@/components/ui/Field";
import { Card } from "@/components/ui/Card";
import { AppHeader } from "@/components/ui/Header";
import { Screen } from "@/components/ui/Screen";
import { Text } from "@/components/ui/Text";
import { DEMO_OTP } from "@/lib/commerce";
import { colors, gutter } from "@/lib/theme";
import { routes } from "@/lib/routes";
import {
  useAuthStore,
  type AuthProvider,
} from "@/lib/stores/authStore";

const DEMO_EMAIL_PASSWORD = "gishen123";

const METHOD_META: Record<
  AuthProvider,
  { title: string; subtitle: string }
> = {
  google: {
    title: "Google",
    subtitle: "Connect with your Google account (demo).",
  },
  email: {
    title: "Email",
    subtitle: `Use any email. Demo password is ${DEMO_EMAIL_PASSWORD}.`,
  },
  phone: {
    title: "Phone",
    subtitle: `We'll send an OTP. Demo code is always ${DEMO_OTP}.`,
  },
  telegram: {
    title: "Telegram",
    subtitle: "Confirm with your Telegram username (demo).",
  },
  guest: {
    title: "Guest",
    subtitle: "Browse without an account.",
  },
};

function normalizeMethod(raw: string | string[] | undefined): AuthProvider {
  const v = Array.isArray(raw) ? raw[0] : raw;
  if (v === "google" || v === "email" || v === "phone" || v === "telegram") {
    return v;
  }
  return "phone";
}

export default function OtpScreen() {
  const { t } = useTranslation();
  const insets = useSafeAreaInsets();
  const params = useLocalSearchParams<{ method?: string }>();
  const method = useMemo(() => normalizeMethod(params.method), [params.method]);
  const meta = METHOD_META[method];

  const signIn = useAuthStore((s) => s.signIn);
  const setHasOnboarded = useAuthStore((s) => s.setHasOnboarded);
  const setBiometric = useAuthStore((s) => s.setBiometric);

  const [name, setName] = useState("Kirukib Abebe");
  const [phone, setPhone] = useState("+251911000000");
  const [email, setEmail] = useState("kirukib@gmail.com");
  const [password, setPassword] = useState("");
  const [telegram, setTelegram] = useState("@kirukib");
  const [code, setCode] = useState("");
  const [sent, setSent] = useState(false);
  const [bio, setBio] = useState(false);
  const [busy, setBusy] = useState(false);

  const finishSignIn = async (payload: {
    name: string;
    phone: string;
    email?: string;
  }) => {
    if (bio) {
      const hw = await LocalAuthentication.hasHardwareAsync();
      if (hw) {
        const res = await LocalAuthentication.authenticateAsync({
          promptMessage: "Enable biometric unlock",
        });
        if (!res.success) {
          Alert.alert("Biometric", "Skipped — you can enable later in profile.");
        }
      }
    }
    signIn({
      name: payload.name.trim(),
      phone: payload.phone.trim(),
      email: payload.email?.trim() || undefined,
      isGuest: false,
      authProvider: method,
    });
    setBiometric(bio);
    setHasOnboarded(true);
    router.replace(routes.home);
  };

  const sendPhoneCode = () => {
    if (!name.trim() || phone.replace(/\D/g, "").length < 9) {
      Alert.alert("Missing info", "Enter your name and a valid phone number.");
      return;
    }
    setSent(true);
    Alert.alert(
      "Code sent (demo)",
      `Use OTP ${DEMO_OTP} to verify. No real SMS is sent in this build.`
    );
  };

  const verifyPhone = async () => {
    if (!sent) return;
    if (code.trim() !== DEMO_OTP) {
      Alert.alert("Invalid OTP", `Enter the demo code ${DEMO_OTP}.`);
      return;
    }
    await finishSignIn({
      name,
      phone,
      email: email.trim() || undefined,
    });
  };

  const signInEmail = async () => {
    if (!name.trim()) {
      Alert.alert("Missing info", "Enter your name.");
      return;
    }
    if (!email.includes("@")) {
      Alert.alert("Invalid email", "Enter a valid email address.");
      return;
    }
    if (password.trim() !== DEMO_EMAIL_PASSWORD) {
      Alert.alert(
        "Wrong password",
        `Demo password is ${DEMO_EMAIL_PASSWORD}.`
      );
      return;
    }
    await finishSignIn({
      name,
      phone: phone.trim() || "+251911000000",
      email,
    });
  };

  const signInSocial = async (provider: "google" | "telegram") => {
    if (!name.trim()) {
      Alert.alert("Missing info", "Enter the name to show on your profile.");
      return;
    }
    if (provider === "telegram" && !telegram.trim()) {
      Alert.alert("Telegram", "Enter your Telegram username.");
      return;
    }
    setBusy(true);
    // Simulated OAuth / Telegram Login Widget handshake
    await new Promise((r) => setTimeout(r, 900));
    setBusy(false);
    const resolvedEmail =
      provider === "google"
        ? email.trim() || `${name.split(" ")[0]?.toLowerCase() || "user"}@gmail.com`
        : email.trim() || undefined;
    const resolvedPhone =
      phone.trim() ||
      (provider === "telegram" ? "+251900000000" : "+251911000000");
    await finishSignIn({
      name: name.trim(),
      phone: resolvedPhone,
      email: resolvedEmail,
    });
  };

  return (
    <Screen>
      <AppHeader title={meta.title} subtitle={meta.subtitle} />
      <View
        style={{
          flex: 1,
          paddingBottom: insets.bottom + 20,
          paddingHorizontal: gutter,
        }}
      >
        {busy ? (
          <View style={{ flex: 1, alignItems: "center", justifyContent: "center", gap: 12 }}>
            <ActivityIndicator size="large" color={colors.brandText} />
            <Text variant="body" color={colors.muted}>
              Connecting to {method === "google" ? "Google" : "Telegram"}…
            </Text>
          </View>
        ) : (
          <>
            <View style={{ marginTop: 8, gap: 12 }}>
              <Field
                label="Full name"
                value={name}
                onChangeText={setName}
                icon="person-outline"
              />

              {method === "phone" ? (
                <>
                  <Field
                    label="Phone"
                    value={phone}
                    onChangeText={setPhone}
                    keyboardType="phone-pad"
                    icon="call-outline"
                  />
                  <Field
                    label="Email (optional)"
                    value={email}
                    onChangeText={setEmail}
                    keyboardType="email-address"
                    autoCapitalize="none"
                    icon="mail-outline"
                  />
                  {sent ? (
                    <Field
                      label="OTP code"
                      value={code}
                      onChangeText={setCode}
                      keyboardType="number-pad"
                      placeholder={DEMO_OTP}
                      icon="key-outline"
                      hint={`Demo code: ${DEMO_OTP}`}
                    />
                  ) : null}
                </>
              ) : null}

              {method === "email" ? (
                <>
                  <Field
                    label="Email"
                    value={email}
                    onChangeText={setEmail}
                    keyboardType="email-address"
                    autoCapitalize="none"
                    icon="mail-outline"
                  />
                  <Field
                    label="Password"
                    value={password}
                    onChangeText={setPassword}
                    secure
                    autoCapitalize="none"
                    icon="lock-closed-outline"
                    hint={`Demo password: ${DEMO_EMAIL_PASSWORD}`}
                  />
                  <Field
                    label="Phone (optional)"
                    value={phone}
                    onChangeText={setPhone}
                    keyboardType="phone-pad"
                    icon="call-outline"
                  />
                </>
              ) : null}

              {method === "google" ? (
                <>
                  <Field
                    label="Google email"
                    value={email}
                    onChangeText={setEmail}
                    keyboardType="email-address"
                    autoCapitalize="none"
                    icon="logo-google"
                    hint="Demo — no real Google OAuth"
                  />
                  <Field
                    label="Phone (optional)"
                    value={phone}
                    onChangeText={setPhone}
                    keyboardType="phone-pad"
                    icon="call-outline"
                  />
                </>
              ) : null}

              {method === "telegram" ? (
                <>
                  <Field
                    label="Telegram username"
                    value={telegram}
                    onChangeText={setTelegram}
                    autoCapitalize="none"
                    icon="paper-plane-outline"
                    placeholder="@username"
                  />
                  <Field
                    label="Phone linked to Telegram"
                    value={phone}
                    onChangeText={setPhone}
                    keyboardType="phone-pad"
                    icon="call-outline"
                  />
                </>
              ) : null}

              <Card padded={false}>
                <SwitchRow
                  icon="finger-print-outline"
                  title={t("common.enableBiometric")}
                  subtitle="Unlock the app faster next time"
                  value={bio}
                  onValueChange={setBio}
                  last
                />
              </Card>
            </View>

            <View style={{ flex: 1 }} />

            {method === "phone" ? (
              !sent ? (
                <Button title={t("common.sendOtp")} onPress={sendPhoneCode} />
              ) : (
                <View style={{ gap: 10 }}>
                  <Button title={t("common.verify")} onPress={verifyPhone} />
                  <Button title="Resend code" variant="ghost" onPress={sendPhoneCode} />
                </View>
              )
            ) : null}

            {method === "email" ? (
              <Button title="Sign in with email" icon="mail-outline" onPress={signInEmail} />
            ) : null}

            {method === "google" ? (
              <Button
                title="Continue with Google"
                icon="logo-google"
                onPress={() => signInSocial("google")}
              />
            ) : null}

            {method === "telegram" ? (
              <Button
                title="Continue with Telegram"
                icon="paper-plane-outline"
                onPress={() => signInSocial("telegram")}
              />
            ) : null}
          </>
        )}
      </View>
    </Screen>
  );
}